The invention relates to a method and apparatus for wrapping palletized loads with stretchable film or other elastic and/or plastic material which owing to the elastic memory of the said wrapping film ensures tight wrappings safely securing the load. The invention can be applied to any known wrapping machine, for instance those in which the load is caused to rotate about a vertical axis, or those in which the load is fixed and the wrapping film feeding equipment rotates around the load itself with an alternate vertical motion at the same time, to make sure the load is tightly wrapped all along its height. The latter machines may be either the type wherein the carriage holding the film reel and pre-stretching rollers rotates on a ring with a vertical or horizontal axis that alternatively moves along such axis, or the type wherein the reel and pre-stretching rollers are mounted so as to be able to move vertically onto the upright of an upside-down xe2x80x9cLxe2x80x9d arm whose upper end can swing around a vertical axis and is supported by a portal structure below which the load to be wrapped is placed.
In these types of equipment the wrapping film leading end is generally held by a fixed clamp placed to the side of the load to be wrapped which opens when the first turns of the wrapping film are overlapped and self-blocked. The wrapping film leading end is so blocked by friction onto the load and into the wrapping itself, which is a solution extremely reliable as well as quick and easy to realize.
Once the wrapping is completed, the film tail is then heat-sealed to the wrapping itself by an external heated plug or by a welder and a counter-welder which is temporarily drawn near the load so as to be then surmounted by the final turns of the wrapping and is then withdrawn on completion of heat-sealing. The heat-sealing of the tail takes some time also because of the cooling that must follow the heating of the material to be heat-sealed and is often a rather difficult operation to be performed owing to the poor consistency of the stretchable film to be heat-sealed. In addition, the final wrapping turns must be arranged in such a way that their consistency and arrangement are suitable for undergoing heatsealing, which implies a rather difficult operation. Moreover, heat-sealing produces harmful gases which are let out in the ambient air.
The invention provides a new method and the related apparatus to fasten the wrapping film tail consisting of:
placing near one side of the load some means on which the final turn/tums of the wrapping rests/rest transversally so as to form a pocket of the correct size in the wrapping wherein such turns are properly spaced from the load;
holding the film, in the zone of the wrapping tail, with a main clamp and a secondary clamp, the said two clamps being not far from each other, the secondary clamp being closer to the load;
cutting the film between two said clamps so as to identify the wrapping tail held by the secondary clamp and the leading end of the subsequent turn held by the main clamp;
placing the secondary clamp holding the wrapping tail into said pocket and then opening such clamp and removing it from such pocket, such operation being correctly phased with, the removal of the means that formed the pocket, so that the pocket, owing to the elastic memory of the wrapping film, will shrink and spread flatly quickly and the length of the film that formed it will incorporate and firmly hold the wrapping tail with no need for heat-sealing. Thus is the wrapping tail friction-blocked by the wrapping itself.